Optical Fiber Raman Amplifiers Research Articles

Effects of ASE noise and dispersion chromatic on performance of DWDM networks using distributed Raman amplifiers

We investigate effects of amplified spontaneous emission noise (ASE), noise figure (NF) and dispersion chromatic on the performance of DWDM networks using distributed optical fiber Raman amplifiers (DRAs) in two different pump configurations, i.e., forward and backward pumping. We found that the pumping configurations, ASE noise, and dispersion play an important role in network performance improving since it reduces noise figure and bit error rate (BER) of the system. Simulation results show that the lowest bit error rate and noise figure when using forward pumping configuration. Moreover, we have also compared ASE noise powers of the simulation with these of the experiment, they are match.

Optimal Design and Performance Study of Optical Fiber Raman Amplifier with Flat Gain

Optical fiber communication is favored by many communication manufacturers because of its low interference, large capacity, long distance and low consumption. Extending the transmission distance of optical fiber communication system will result in attenuation loss. Therefore, it is necessary to improve the incident power of the initial optical fiber, but it will be affected by Raman scattering effect, thus reducing the performance of the overall optical fiber communication system. In order to overcome the above problems, Raman amplifier is used to pump high-power short-wavelength light wave and amplify long-wavelength and low-power signals, but the flattening of signal gain needs to be considered. In this study, the working principle of Raman amplifier is introduced, the Raman pump module is optimized, the system architecture of the module is studied, and the module circuit is designed. It mainly covers the structure design, driving circuit design and auxiliary circuit design of the module. In the experimental process, based on the transmission coupling equation of the fiber Raman amplifier, the distribution of pump and signal power on the fiber is calculated by numerical analysis. By optimizing the pump module, the gain flatness of the amplification system is optimized, and the signal gain of the whole fiber communication system is reduced by more than 80%. It proves that the optimal design of fiber Raman amplifier proposed in this study is effective and can achieve the overall stability of signal reception in the application of optical fiber communication system.

Suppression of Stimulated Brillouin Scattering in Single-Frequency Fiber Raman Amplifier Through Pump Modulation

We propose and implement the use of an intensity-modulated pump, counter-directional to a forward-propagating signal for suppressing unwanted stimulated Brillouin scattering (SBS) of spectrally narrow signals in optical fiber Raman amplifiers. The modulated Raman pump cross-phase modulates and thus spectrally broadens the parasitic Brillouin Stokes wave traveling in the same (backward) direction. The parasitic SBS then decreases when the broadening exceeds the Brillouin gain bandwidth. By contrast, the modulated pump does not induce any significant cross-phase modulation on the signal, which therefore can remain spectrally narrow. We study the effect of the pump modulation frequency and modulation format and experimentally obtain nearly 5 dB of SBS threshold enhancement and over 50 $\%$ pump-to-signal conversion efficiency.

The Spectral Gain Characteristics of Optical Fiber Weak Light Pre-Amplifier Based on Raman Effect

The spectral information of weak light will be lost in the process of amplification based on photoelectric conversion. To solve this problem, multi-wavelength optical fiber Raman amplifier is used to pre-amplify the weak light before an ordinary color photoelectric sensor. The Raman gains and their effect factors were modeled and analyzed. The results show high intensity gains can be obtained for red, green and blue components of the weak light simultaneously .

Performance Optimization Based Spectrum Analysis on Optical Fiber Raman Amplifier with Both Backward and Bidirectional Pumping

Performance Optimization Based Spectrum Analysis on Optical Fiber Raman Amplifier with Both Backward and Bidirectional Pumping

High Performance Efficiency of Distributed Multi Pumped Wide Gain Optical Fiber Raman Amplifiers

High Performance Efficiency of Distributed Multi Pumped Wide Gain Optical Fiber Raman Amplifiers

Performance Optimization Based Spectrum Analysis on Optical Fiber Raman Amplifier with Backward Pumping

Optical fiber Raman amplifier (OFRA) with wide and flat gain bandwidth has been widely applied in the fields of optical communication, sensing and measurement. However, the performance optimization is always one of the hot topics in the study of OFRA, because its output characteristics are hardly dependent to some key designing parameters. In this paper, to overcome the problems above, we adopt a spectrum analysis based method to study the output performance of an OFRA system with backward pumping. By simulating the operation of the OFRA system, its output characteristics are first showed easily, with the advantages of real time, low cost, and low complexity. Further, according to the numerical results obtained, the optimal parameters of an OFRA system are determinate, and the performance in terms of output power, signal noise ratio, and the level of gain flatness is improved and optimized obviously.

Recent Advances of Distributed Optical Fiber Raman Amplifiers in Ultra Wide Wavelength Division Multiplexing Telecommunication Networks

Recent Advances of Distributed Optical Fiber Raman Amplifiers in Ultra Wide Wavelength Division Multiplexing Telecommunication Networks

High performance efficiency of distributed optical fiber Raman amplifiers for different pumping configurations in different fiber cable schemes

Fiber Raman amplifiers (FRAs) are attractive for ultra wide dense wavelength division multiplexing (UW-DWDM) transmission systems due to their advantages of broad amplification bandwidth and flexible central wavelength. With recent developments of optical pump sources with high power near 1.4 μm wavelength and highly nonlinear fiber having a peak effective Raman gain coefficient, more than ten times that of conventional single mode fiber, distributed FRAs (DFRAs) are emerging as a practical optical amplifier technology, especially for opening new wavelength windows such as the short and ultra long wavelength bands. Optical pump powers required for Raman amplification were significantly higher than that for erbium-doped fiber amplifier (EDFA), and the pump laser technology could not reliably deliver the required powers. However, with the improvement of pump laser technology, Raman amplification is now an important means of expanding span transmission reach and capacity. In the present paper, we have deeply investigated the proposed model for optical DFRAs in the transmission signal power and pump power within Raman amplification technique in co-pumped, counter-pumped and bi-directional pumping direction configurations through different types of fiber cable media. The validity of this model was confirmed by using experimental data and numerical simulations. Key words: Distributed fiber Raman amplifier, signal power, pumping power, forward pumping, different fiber media, backward pumping, bidirectional pumping configuration.

Recent advances of distributed optical fiber Raman amplifiers in ultra wide wavelength division multiplexing telecommunication networks

Recently, many research works have been focused on the fiber optic devices for optical communication systems. One of the main interests is on the optical amplifiers to boost a weak signal in the communication systems. In order to overcome the limitations imposed by electrical regeneration, a means of optical amplification was sought. The competing technology emerged: the first was Raman amplification. One reason was that the optical pump powers required for Raman amplification were significantly higher than that for Erbium doped fiber amplifier (EDFA), and the pump laser technology could not reliably deliver the required powers. However, with the improvement of pump laser technology Raman amplification is now an important means of expanding span transmission reach and capacity. We have deeply studied an analytical model for optical distributed Raman amplifiers (ODRAs) in the transmission signal power and pump power within Raman amplification technique in co-pumped, counter-pumped, and bi-directional pumping direction configurations through different types of fiber cable media. The validity of this model was confirmed by using experimental data and numerical simulations. Key words: Distributed Raman amplifier, fiber link media, signal power, pump power, and Raman gain efficiency.

Ultra wide band (UWB) of optical fiber Raman amplifiers in advanced optical communication networks

In the present paper, we have analyzed numerically the ultra wide band (UWB) optical fiber Raman amplifiers in advanced optical communication networks. Moreover, we have developed the numerical transmission and propagation techniques based on mathematical laboratory programming to solve the coupled optical wave equations to obtain design parameters, operational characteristics, and its implementation in the light wave modulated envelop propagation equations for transmission of multi Gbit/sec signals in dense wavelength division multiplexing optical communication systems. We have investigated numerically and parametrically the soliton transmission technique to handle the bit rates and products either per link or per channel in all pumping direction configurations to upgrade optical network efficiency in order to support ultra high capacity of number of users. Also, we have concentrated on the fiber Raman optical amplifier is quickly emerging as an important part of ultra long-distance, high-capacity, and high-speed optical communication systems. Key words: Raman amplification technique, advanced optical networks, ultra wide-band, dense wavelength division multiplexing (DWDM), space division multiplexing (SDM).

Correction to "Exact Analytical Solution for Raman Fiber Laser"

In the above paper [ibid.,vol. 18, no. 9, pp. 1097–1099, May 1, 2006], the Raman fiber laser was modeled and an analytical solution, verified by numerical simulations and an experimental demonstration, was obtained. In the theoretical analysis of the fiber Raman laser, the pump power evolution was expressed using the known Lambert W function and then the lasing power given by (7) was solved using the Newton–Raphson method, like Dr. Santagiustina had previously done in the case of fiber Raman amplifiers [see Exact integral solution of saturation and depletion in forward and backward optical fiber Raman amplifiers, Opt. Lett., vol. 32, no. 20, pp. 3023–3025, Oct. 2007.]. We sincerely apologize for our negligence to cite the prior work of Dr. Santagiustina in our paper. This correction is provided to give proper credit to Dr. Santagiustina's work, which was originally submitted to Optics Letters in 2005 and published in 2007.

A moment method for analysis the gain spectrum in fiber Raman amplifier with broadband pumps

The governing equations of optical fiber Raman amplifier with broadband pumps in the steady state are systems of uncountable nonlinear ordinary differential equations (NODE). In this paper, the Moment method is used to reduce the uncountable system of NODE to a system of finite number of NODE. This system of equations is solved numerically. The results are compared with that of the full numerical method. It was shown that the Moment method is a precise and efficient technique for analysis of optical fiber Raman amplifier with broadband pumps.

Exact integral solution of saturation and depletion in forward and backward optical fiber Raman amplifiers

Exact integral solutions of forward and backward Raman Stokes-pump interaction are presented. They enable one to determine the gain and depletion characteristics of optical Raman amplifiers, as well as a good approximation of the noise figure, without the need of numerically solving the nonlinear boundary value differential equations governing the Raman interaction.

Performance improvement of fiber Raman amplifiers using time-division-multiplexed pumping

A novel kind of optical fiber Raman amplifiers using time-division-multiplexed (TDM) pumping is analyzed. The equations governing the evolution of the pumps and signals are presented for both TDM forward and TDM backward pumping. Simulation results show that the performance in gain profile and ASE noise figure can be effectively improved. The optimal TDM pump repetition rates are between 2 and 8 MHz.

Optimal Position of Isolator to Suppress Double Rayleigh Backscattering Noise in Fiber Raman Amplifiers

In this paper, amplified double Rayleigh backscattering noise (DRB) in the optical fiber Raman amplifier is analyzed. Expressions are present for both forward pumping and backward pumping schemes, respectively. Calculation is performed to show the effective suppression of DRB noise by employing an optical isolator. The best isolator position is determined as 13 km away from the signal input end for forward pumping, and 9 km from the output end for backward pumping. The best position is found insensitive to the fiber length, pump power, and signal power. When the isolator is on the best position, the DRB noise can be reduced by almost 2 to 3 orders.

Analysis of ASE Noise in Optical Fiber Raman Amplifiers

In this paper, ASE (amplified spontaneous emission) noise induced by parametric gain and spontaneous Raman scattering in optical fiber Raman amplifier is analyzed. Expressions regarding the generation and amplification of such kind of noise are present. Simulations are carried out on a forward WDM pumping fiber Raman amplifier and a long haul transmission system with multi-stage fiber Raman amplifiers. Results show that parametric gain induced ASE noise is the main part of ASE noise. Its spectrum is wider and its power is higher than those of spontaneous Raman scattering induced ASE noise.

New design scheme for multiple‐pump Raman fiber amplifiers using a simulated annealing algorithm

AbstractA simulated annealing algorithm is adopted to design multiple‐pump Raman fiber amplifiers. A demonstration of the optical fiber Raman amplifier using five laser diode pumps with different wavelengths and powers is presented. The automatic configuration of the pump gives an amplification bandwidth of more than 50 nm (64 signal channels), with a fluctuation of less than 1.8 dB. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 434–436, 2001.

Pump depletion induced noise and crosstalk in distributed optical fiber Raman amplifiers

In distributed optical fiber Raman amplifiers, instantaneous pump power depletion is related to the patterns of the input wavelength-division-multiplexing signals, especially for high bit rate application. This results in additional optical noise and interchannel crosstalk. We analyzed the phenomenon and presented simulation results. The cases for different bit rates and channel numbers were compared.

Recent advances in optical fiber Raman amplifiers

Recent advances in optical fiber Raman amplifiers